High-precision large-aperture shaft current testing device

Abstract

The utility model relates to a high-precision large-aperture shaft current testing device which comprises a fluxgate current testing ring, a supporting seat, a circuit control box and a recorder, the fluxgate current testing ring is fixedly connected to a motor end cover through the supporting seat, the fluxgate current testing ring is electrically connected with the circuit control box, and the circuit control box is electrically connected with the recorder; the fluxgate current testing ring comprises two semicircular magnetic cores, enameled wires and a metal shielding shell, each semicircular magnetic core is formed by superposing high-magnetic-conductivity metal sheets, the two semicircular magnetic cores are uniformly wound with the enameled wires with the same number of turns and the same size, and the metal shielding shell is wound with the enameled wires. The two semicircular magnetic cores wound with the enameled wires are symmetrically fixed in the metal shielding shell; and the enameled wires on the two semicircular magnetic cores are combined into two groups of coils which are electrically connected to the circuit control box respectively. According to the utility model, the shaft current of a small-current and large-rotating-shaft motor can be accurately measured, and the size of the test ring is not limited.

Description

TECHNICAL FIELD

[0001] The utility model relates to generator test technical field especially, it is a kind of high-precision large aperture shaft current testing device. BACKGROUND

[0002] At present, motor drive system adopts the power converter of pulse width modulation technology (PWM), the power converter has the advantages such as wide speed regulation range, dynamic response fast, but the IGBT high-speed switching device used in its system can produce high-frequency common-mode voltage, the common-mode voltage produces shaft voltage and forms shaft current through motor rotating shaft, leading to motor bearing electric corrosion;With the application of new generation SiC converter, motor bearing will be in stronger electric field environment.Therefore, bearing electric corrosion problem seriously restricts the safe and reliable use of motor.

[0003] In recent years, although some converter, motor and complete machine manufacturers have optimized from converter modulation strategy, motor body structure and complete machine grounding circuit etc., due to the large size of motor rotating shaft, and lack of high-precision shaft current testing equipment, so there is no suitable testing equipment to obtain accurate shaft current data and threshold value, so as to formulate effective shaft current suppression strategy, so bearing electric corrosion phenomenon is still serious.

[0004] The commonly used shaft current test sensor is a Rogowski coil, and the sensor is mainly based on Faraday's law of electromagnetic induction and Ampere's law.The sensor has the advantages of wide frequency range, simple structure, easy installation etc.;But the sensor has low measurement accuracy, can only accurately measure large current of ampere level, and cannot accurately measure small current of milliamper level, and can only measure alternating current.

[0005] In view of this, the utility model provides a kind of high-precision large aperture shaft current testing device, the device realizes the measurement of shaft current based on deep negative feedback zero flux technology, with the advantages of high precision, wide measurement range, AC and DC can be measured, test ring size is not limited, simple structure and installation etc. Small current, the shaft current of large rotating shaft motor can be accurately measured. INVENTION CONTENTS

[0006] In order to realize the accurate measurement of shaft current of small current and large rotating shaft motor and ensure that the size of test ring is not limited, the utility model provides a kind of high-precision large aperture shaft current testing device.

[0007] The high-precision large aperture shaft current testing device provided by the utility model adopts the following technical scheme:

[0008] The utility model provides a high accuracy big aperture shaft current testing arrangement, including magnetic flux gate current test ring, support seat, circuit control box and wave recording appearance, the magnetic flux gate current test ring is fixedly connected on motor end cover through the support seat, magnetic flux gate current test ring with circuit control box electricity is connected, and circuit control box with wave recording appearance electricity is connected, the magnetic flux gate current test ring includes semicircular magnetic core, enameled wire and metal shielding casing, the semicircular magnetic core is provided with two, and the semicircular magnetic core is made of high magnetic permeability metal sheet superposition, and the enameled wire is uniformly arranged on two semicircular magnetic cores with same number of turns and size, and the two semicircular magnetic cores with enameled wire are fixed in the metal shielding casing, and the enameled wire on two semicircular magnetic cores is combined into two groups of coils and is electrically connected to the circuit control box.

[0009] Preferably, the metal shielding casing is in the shape of a whole ring, and a plurality of mounting blocks are uniformly arranged on the sidewall of the metal shielding casing in the circumferential direction, and at least one mounting hole is formed in each mounting block and adapted to the opening in the motor end cover.

[0010] Preferably, the magnetic flux gate current test ring is designed and assembled in one piece or in a spliced manner according to the size of the motor rotating shaft.

[0011] Preferably, the two groups of coils are electrically connected to an aviation plug, the aviation plug is electrically connected to the circuit control box through four-core wires, and the circuit control box is electrically connected to the wave recording appearance through a BNC connecting line.

[0012] Preferably, the magnetic flux gate current test ring has a test range of 1mA-1000A, a test precision of 10ppm-5%, a test frequency of 0-500KHz, and a working temperature of-40℃-125℃.

[0013] In summary, the utility model has at least one of the following beneficial technical effects:

[0014] 1. When the utility model is used, the shaft current is measured based on the deep negative feedback zero flux technology, and the utility model has the advantages of high precision, wide measurement range, AC and DC measurement, unlimited size of the test ring, simple structure and installation, etc., and can accurately measure the shaft current of a small-current large-rotating-shaft motor. BRIEF DESCRIPTION OF DRAWINGS

[0015] Fig. 1 is a structural schematic view of a high-precision large-aperture shaft current testing device provided by the utility model;

[0016] Fig. 2 is a structural schematic view of a magnetic flux gate current test ring provided by an embodiment of the utility model;

[0017] Fig. 3The utility model provides a high accuracy big aperture shaft current testing arrangement's test principle diagram.

[0018] Sign:1, magnetic flux gate current test ring, 11, semicircular magnetic core, 12, enameled wire, 13, metal shielding casing, 2, support seat, 3, circuit control box, 4, wave recorder, 5, mounting block, 51, mounting hole, 6, aviation plug, 7, four core electric wire, 8, motor rotating shaft, 9, motor end cover. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantage of the utility model embodiment more clear, the technical scheme of the utility model embodiment will be clearly and completely described below in conjunction with the drawings of the utility model embodiment. Obviously, the described embodiment is a part of the embodiment of the utility model, not all the embodiment. Based on the described embodiment of the utility model, all other embodiments obtained by the person skilled in the art without creative labor belong to the scope of the utility model protection.

[0020] Unless otherwise defined, the technical terms or scientific terms used here should be understood as the usual meaning of the person skilled in the art of the utility model. The "one" or "a" and similar words used in the utility model patent utility model specification and claims do not represent quantity limitation, but represent the existence of at least one.

[0021] The following will be combined with the drawings of the utility model Figs. 1-3 The utility model will be further explained in detail.

[0022] The utility model embodiment discloses a high accuracy big aperture shaft current testing device.

[0023] Refer to Figs. 1-3 A kind of high accuracy big aperture shaft current testing device, including magnetic flux gate current test ring 1, support seat 2, circuit control box 3 and wave recorder 4, magnetic flux gate current test ring 1 is fixedly connected on motor end cover 9 by support seat 2, motor rotating shaft 8 is rotatably connected with motor end cover 9 by bearing outer cover and bearing, motor rotating shaft 8 is threaded through magnetic flux gate current test ring 1, magnetic flux gate current test ring 1 is electrically connected with circuit control box 3, circuit control box 3 is electrically connected with wave recorder 4.

[0024] The magnetic flux gate current test ring 1 comprises a semicircular magnetic core 11, an enameled wire 12 and a metal shielding shell 13, the semicircular magnetic core 11 is installed with two semicircular magnetic cores 11 of the same size, the semicircular magnetic core 11 is stacked by high magnetic permeability metal sheets, two groups of enameled wires 12 of the same size are uniformly wound on the two semicircular magnetic cores 11, the metal shielding shell 13 is in the shape of a whole ring, the two semicircular magnetic cores 11 wound with the enameled wires 12 are placed in the metal shielding shell 13, and the relative positions of the semicircular magnetic cores 11 and the metal shielding shell 13 are fixed by pouring sealing glue; the enameled wires 12 on the two semicircular magnetic cores 11 are combined into two groups of coils and are electrically connected to the circuit control box 3 respectively, in the embodiment, the magnetic flux gate current test ring 1 is designed and assembled in an integrated or spliced manner according to the specific size of the motor rotating shaft 8.

[0025] During the test, the change of the magnetic field is sensed by one group of coils, the sensed signal is fed back through an integral feedback circuit and a driving circuit, the other group of coils outputs a current signal, so that the inside of the semicircular magnetic core 11 reaches a zero magnetic flux state. The output current signal passes through a sampling resistor, and then the voltage across the sampling resistor is differentially amplified and converted into a required voltage value, so that the size of the shaft current of the motor to be tested can be fed back in real time.

[0026] With reference to Fig. 2 A plurality of mounting blocks 5 are uniformly arranged on the side wall of the metal shielding shell 13 in the circumferential direction, at least one mounting hole 51 adapted to the opening on the motor end cover 9 is formed in the mounting block 5, the metal shielding shell 13 is fixedly connected to the support base 2 through bolts, and then the support base 2 is fixedly installed on the motor end cover 9 through bolts, so that the magnetic flux gate current test ring 1 can be installed in the motor.

[0027] With reference to Fig. 1 Further, the two groups of coils are electrically connected to the aviation plug 6, the aviation plug 6 is electrically connected to the circuit control box 3 through four-core wires, and the circuit control box 3 is electrically connected to the wave recorder 4 through a BNC connecting line. In an available embodiment, the wave recorder 4 can also be replaced by an oscilloscope, so that the specific value and waveform of the measured motor shaft current can be displayed in real time. In the embodiment, the aviation plug 6 and the four-core wire 7 are both prior art, and will not be described in detail.

[0028] Further, the test range of the magnetic flux gate current test ring 1 is in the range of 1mA-1000A, the test precision is in the range of 10ppm-5%, the test frequency is in the range of 0-500KHz, and the working temperature is set in the range of -40℃-125℃.

[0029] The working principle of the high-precision large-aperture shaft current test device is as follows:

[0030] Based on the measured current generated by the magnetic field on the high permeability magnetic core in the saturation excitation of alternating magnetic field, the nonlinear relationship between the magnetic induction intensity and the magnetic field intensity, this physical phenomenon on the measured magnetic field seems to be a "door", through this "door", the corresponding magnetic flux is modulated, and the induced electromotive force is generated. Using this phenomenon to measure the magnetic field generated by the current, thereby indirectly achieving the purpose of measuring the current. The flux gate current sensor is based on the current sensor technology of deep negative feedback zero flux technology, which is the combination of self-balancing comparator and magnetic integrator technology for precise measurement. It can not only measure direct current large current with high precision, but also has very excellent response speed and frequency bandwidth.

[0031] The above are preferred embodiments of the present application, and are not intended to limit the protection scope of the present application, therefore: any equivalent changes made according to the structure, shape, principle of the present application should be covered within the protection scope of the present application.

Claims

1. A high-precision large-aperture shaft current testing device, characterized in that, It includes a fluxgate current test ring (1), a support seat (2), a circuit control box (3) and a wave recorder (4), the fluxgate current test ring (1) is fixedly connected on the motor end cover (9) through the support seat (2), the fluxgate current test ring (1) is electrically connected with the circuit control box (3), and the circuit control box (3) is electrically connected with the wave recorder (4); The fluxgate current test ring (1) includes two semicircular magnetic cores (11), enameled wires (12) and a metal shielding shell (13), the two semicircular magnetic cores (11) are arranged, the semicircular magnetic core (11) is made of high magnetic permeability metal sheets, the two semicircular magnetic cores (11) are uniformly provided with the enameled wires (12) with the same number of turns and size, and the two semicircular magnetic cores (11) provided with the enameled wires (12) are fixedly arranged in the metal shielding shell (13); the enameled wires (12) on the two semicircular magnetic cores (11) are combined into two groups of coils and are electrically connected to the circuit control box (3) respectively.

2. The high-precision large-aperture shaft current testing device according to claim 1, characterized in that: The metal shielding shell (13) is in the shape of a whole ring, a plurality of mounting blocks (5) are uniformly arranged on the side wall of the metal shielding shell (13) in the circumferential direction, and at least one mounting hole (51) matched with the opening of the motor end cover (9) is formed in the mounting block (5).

3. The high-precision large-aperture shaft current testing device according to claim 1, characterized in that: The fluxgate current test ring (1) is designed and assembled in an integrated or spliced manner according to the specific size of the motor rotating shaft (8).

4. The high-precision large-aperture shaft current testing device according to claim 1, characterized in that: The two groups of coils are electrically connected with an aviation plug (6), the aviation plug (6) is electrically connected with the circuit control box (3) through four-core wires, and the circuit control box (3) is electrically connected with the wave recorder (4) through a BNC connecting line.

5. The high-precision large-aperture shaft current testing device according to claim 1, characterized in that: The fluxgate current test ring (1) has a test range of 1mA-1000A, a test precision of 10ppm-5%, a test frequency of 0-500KHz and a working temperature of-40℃-125℃.

Images